a. Field of the Invention
This invention relates to systems and methods for ablation of cardiac tissue in a living being. In particular, the instant invention relates to systems and methods for ablation of cardiac tissue via the esophagus using photodynamic therapy.
b. Background Art
It is well known to use ablation catheters to create tissue necrosis in cardiac tissue to correct conditions such as atrial arrhythmia (including, but not limited to, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter). Arrhythmia can create a variety of dangerous conditions including irregular heart rates, loss of synchronous atrioventricular contractions and stasis of blood flow which can lead to a variety of ailments and even death. It is believed that the primary cause of atrial arrhythmia is stray electrical signals within the left or right atrium of the heart. The ablation catheter imparts ablative energy (e.g., radiofrequency energy) to the heart tissue to create a lesion in the heart tissue. This lesion disrupts undesirable electrical pathways and thereby limits or prevents stray electrical signals that lead to arrhythmias.
Ablation catheters are typically placed near the cardiac tissue to be treated in one of two ways. Access to endocardial tissue is obtained by inserting the catheter within a vessel located near the surface of a patient's body (e.g., in an artery or vein in the leg, neck, or arm) and maneuvering the catheter through the circulatory system to the internal heart chambers. Access to epicardial tissue may be obtained by making a subxiphoid incision in the patient's body. Although the use of ablation catheters in this manner has resulted in less invasive treatment of arrhythmias, it would be desirable to develop a system and method for treatment of cardiac tissue that is even less invasive than current methods.
A need exists for systems and methods for ablation of cardiac tissue that will minimize and/or eliminate one or more of the above-identified deficiencies. A need also exists for providing feedback to the physician or other user of the systems and methods. Prior to lesion formation, for example, the physician or other user may desire to know that the ablation catheter is properly positioned adjacent the tissue to be ablated, that the ablation catheter can be maintained in the desired position during the ablation procedure, that the ablation catheter is not itself causing damage to the surrounding tissue. Following the lesion formation, for example, the physician or other user may desire to know that the ablation lesion has been successfully formed, in the desired position, and is the desired length, so that the procedure will not need to be repeated.